#include <fstream>

using namespace std;
int n,i,ok,v[1000003],j,minim,k;
long long sol;
ifstream fin ("operatii.in");
ofstream fout ("operatii.out");

int main (){

    fin>>n;
    for (i=1;i<=n;i++)
        fin>>v[i];
    for (i=1;i<=n;i++){
        if(v[i] > v[i-1])
            sol += v[i]-v[i-1];
    }
    fout<<sol;
  /*  for (;;){
        ok = 0;
        i = 1;
        while (v[i] == 0 && i<=n)
            i++;
        j = i;
        minim = 2000000000;
        while (v[i] != 0 && i<=n){
            if (v[i] < minim)
                minim = v[i];
            i++;
            ok = 1;
        }
        // j ..... i-1 decrementam cu minim si adaugam minim la solutie
        if (minim != 2000000000){
            for (k=j;k<i;k++)
                v[k] -= minim;
            sol += minim;
        }
        else
            break;


        if (ok == 0)
            break;
    }
    fout<<sol;
*/

    return 0;
}